2020.10.25 update

南大镜像源: https://mirrors.nju.edu.cn/ubuntu/
使用手册: https://nju-mirror-help.njuer.org/ubuntu.html
自己学校的镜像源用起来还是快很多
=======================================

更换apt-get数据源

1. 输入：sudo -s切换为root超级管理员；
2. 执行命令：vim /etc/apt/sources.list；(保险起见，建议先执行cp /etc/apt/sources.list /etc/apt/sources.list.bak进行备份)
3. 使用命令：%d 清空所有内容；
4. 清华数据源地址：https://mirrors.tuna.tsinghua.edu.cn/help/ubuntu/ 选择相应的版本复制内容，点击“i”键进入编辑文本模式，粘贴内容到vim编辑窗体，点击“ESC”键进入编辑模式，输入“:wq”保存离开；

清华源（以Ubuntu 16.04为例)：

# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted universe multiverse

# 预发布软件源，不建议启用
# deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse

南大源(Ubuntu 16.04):

# 默认注释了源码仓库，如有需要可自行取消注释
deb https://mirrors.nju.edu.cn/ubuntu/ xenial main restricted universe multiverse
# deb-src https://mirrors.nju.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb https://mirrors.nju.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
# deb-src https://mirrors.nju.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb https://mirrors.nju.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
# deb-src https://mirrors.nju.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb https://mirrors.nju.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
# deb-src https://mirrors.nju.edu.cn/ubuntu/ xenial-security main restricted universe multiverse

# 预发布软件源，不建议启用
# deb https://mirrors.nju.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse
# deb-src https://mirrors.nju.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse

5. 更新源：sudo apt-get update
6. 更新软件：sudo apt-get upgrade

BTW，阿里的镜像站:https://opsx.alibaba.com/
清华镜像站:https://mirrors.tuna.tsinghua.edu.cn/